And I'm Renee Montagne. Enrollment in the government's new health insurance website picked up last month, after a disastrous start in October. Still, the number of people signing up for coverage is below the administration's original forecast. Health Secretary Kathleen Sebelius is likely to be grilled about the website and other challenges when she testifies this morning before a House subcommittee. And for more on all of that, NPR's Scott Horsley joins us now. Good morning.

SCOTT HORSLEY, BYLINE: Good morning, Renee.

MONTAGNE: Now, the government has just released sign-up numbers for the month of November. What do they show?

HORSLEY: As of November 30th, Renee, about 137,000 people had signed up for insurance coverage through the federal website, another 227,000 in the exchanges run by 14 states and the District of Columbia. Now, that's a sharp jump from October. In the case of the federal website, it's about a four-fold increase. But, of course, the site was barely functional in October. So that was a pretty low bar. The total enrollment through October and November is now about 365,000. That's below the half-million that the government initially expected for October alone. So while the pace is picking up, there's a lot of ground to make up. Michael Hash, who directs the Office of Health Reform at the Health and Human Services department, says they expect the pace of enrollments to keep growing now that the website is working better.

MICHAEL HASH: The HealthCare.gov website is night and day from where it was on October the 1st. The majority of users are now able to move smoothly through the application process, and it's now easier than ever to shop for and compare plans and to enroll in coverage.

HORSLEY: Now, these numbers just go through the end of November, and a lot of the technical fixes came at the very end of that period. In the first 10 days or so of December, there has been heavy traffic on the site. Just in the first two days this week, some 800,000 people logged on.

MONTAGNE: Well, all right. And the next couple of weeks could also be very busy, because we're up against a deadline, right?

HORSLEY: Right. Consumers have till December 23rd to sign up for coverage that would take effect at the beginning of January. That's the first big milestone, when there's a real incentive to get this done. Then there's another milestone at the end of March. That's when folks who don't have insurance have to sign up in order to avoid a tax penalty. Now, the administration initially said they expected seven million enrollments by end of March, and even with the very slow start, Hash says he still believes they're on track to meet that target.

HASH: Based upon experience such as that in Massachusetts, we expect that a bulk of enrollees will occur toward the end of the open enrollment period.

HORSLEY: Now, of course, success depends not just on how many people sign up, but the mix of people. They want young, healthy folks to help offset the cost of older, sicker people. And, unfortunately, the federal government has not given us any numbers on the mix yet. Some states have. So it is possible to show these numbers. But the federal government hasn't done that yet.

MONTAGNE: So, Scott, more people are visiting the website. Many of them are navigating the process successfully. They're signing up for coverage. But are we sure that they will actually have insurance come January 1st?

HORSLEY: Well, of course, that's the goal. And as we've reported, there had been problems on the back end of the website, the part that provides information to insurance companies. Initially, as many as one in four enrollment forms had errors in them. That's now down to one in 10. But the government still has a ways to go to get that problem fixed, so that the people who sign up actually get the coverage they think they're signing up for. If not, another black eye for the insurance exchanges.